William



UNITED STATES PATENT OFFICE.

ILLIAM C. MURDOCK, F \VASHING'ION, DISTRICT OF (OII M BIA, ASSIGNORTOTHE NATIONAL YULUANITE COMPANY, OF NElV YORK, N. Y.

VULCANITE PAVING COMPOUND.

SPECIFICATION forming part of Letters Patent No. 394,126, dated December4, 1888. Application filed May 16, 1888. Serial No. 274,093. (Nospecimens.)

To aZZ whom it may concern.-

Be it known that I, WILLIAM (J. MURDocK, of \Vashington, in theDistrictot Columbia, have invented certain new and useful Improvemeutsin Vulcanite Paving Compounds; and I do hereby declare the following tobe a full, clear, and exact description of the same.

This invention relates to thepreparation and combimttion of materials toform what is IO known as vulcanite pavement-a composition employedt'orpaving streets, sidewalks, cellars, stables, &c.; and it consists in thenovel and improved compositions and mode of treatment of the materialsforming part I5 thereof, as hereinafter described, and pointed out inthe claims.

In the preparation of asphalt pavements it has heretofore been customaryto prepare the asphalt by subjectin crude Trinidad asphalt in kettles orretorts to a tire heat of from 700 to 1,000 I ahrenheit, for the purposeof melting the mass to precipitate the earthy and other matterscontainml therein and driving olt moisture. To the melted asphalt petro-2 5 leum residuum is added in the proportion of about one part residuumto six parts asphalt, and the whole being subjected to heat andagitation produces what is known as petro leum-asphalt cement. By reasonof the high 0 degree of heat heretofore deemed i'lecessary in carryingout this process the heavier essential oils are driven oil, to thedetriment of the compound and injury of the pavement made therefrom, asthe heavy hydrocarbons which 3 5 are necessarily expelled, instead ofbeing detri mental, are exceedingly valuable in maintaining the lite andtenacity of the matrix, and their removal renders the residuum brittle,more liable to be injured by exposure to the atmospheric influences, aswell as being more friable, and thus more readily destroyed and wornaway when subjected to heavy or constant traffic, as in large cities. Tocounteract or in a measure compensate for the loss of the oils drivenoff in the preparation otthe asphalt, petroleum residuum is added;butthis again being subjected to the high heat is in turn deprived of alarge portion of its more volatile oils hence it sometimes becomes nec-5o essary 61' advisable to add in the subsequent treatment a certainproportion of petroleum residuum. As is well known, petroleum andpetroleum residuum contain active solvents of bituminous matter, and itsettect upon the asphalt, especially when the former contains the lighteroils, is of such a nature as to render it extremely dit'ticult andpractically impossible to thoroughly unite the asphalt cement withartificial asphalts made from coaltar or such as contain theseartificial asphalts in large proportions. As the result of muchexperience and many trials, I have discovered that it is possible toavoid or counteract these defects both as to the manufacture and productby substituting coal-tar residuum for pe- 6 5 troleum residuum andsubjectingthe crude asphalt to a temperature not exceeding 500"liahrenheit.

In practicing this part of my invention I place the crude naturalasphalt in a retortor other vessel and add the coal-tar distil1ate i.6., coal-tar deprived of the lighter oilsin about the proportion ofseven parts of the former to one of the latter, and heat the mixture toa temperature of 450" Fahrenheit, re- 7 5 taining it at or about thistemperature, but never exceeding 500" Fahrenheit, until the asphalt hasbeen con'ipletely melted or amalgamated with the coal-tar distillate. Inthis way I manage to preserve all thedesirable 8o qualities andconstituents of both the asphalt and coal-tar, while eliminatin thelighter oils,

or such as in practice have been found deleterious or destructive to thelife of the pavement, at the same time eifecting a complete admixture ofthe two substances. The addition of the coal-tar distillate to theasphalt also assists materially in expediting the liquefaction andsolution of the asphalt when subjected to the relatively low temperatureem- 0 ployed.

The mixture is maintained at a practically uniform temperature of 450Fahrenheit until evaporation ceases, and it is then in condition toreadily and naturally combine with most, if not all, of the bituminouscompounds, such as are employed for paving and similar purposes.

To form my improved pavingcompound or mixture, the asphalt thus producedis united 10o with distillate of coal -tar which has previously beensubjected to a temperature not exceeding 450 Fahrenheit to drive off themore volatile oils, the proportions employed being approximately seventyparts of the distillate to thirty parts of the asphalt, forming 'anasphaltic cement possessing uniform properties and retaining all theheavier hydrocarbon oils and compounds not evaporatin at the temperatureto which the materials have been subjected,i. 6., 450 Fahrenheit.

Having thus produced my asphaltic cement, I proceed to prepare theingredients which, when combined therewith in the manner and proportionsspecified, constitute the paving material. These materials oringredients are clean, fine, and sharp sand, carbonate of lime, sulphur,sulphate of calcium, mineral wool or asbestus, l1 "dlL1lllG cement,calcareous gravel, and stone dust in proportions varying with theclimate and service to which. the pavement is to be subjected, theproportions also varying somewhat according to the relative coarsenessor fineness of the materials used. Thus, to form the wearing-surface Imay employ seventy parts sand, one part hydraulic cement, ten

parts calcareous gravel, one part sulphur, six

parts carbonate of lime, six parts sulphate of calcium, two partsmineral wool or asbestus, and six parts stone dust. These ingredientsare thoroughly mixed and heated to a temperature not exceeding 250Fahrenheit, but pref rably at 230 Fahrenheit, and to this heated mixtureI add at the same temperature a sufficient quantity of the asphalticcement, prepared as described, to 'form the required wearingsurface.

The quantity of asphaltic cement will necessarily vary somewhat with theclimate and thickness of the wearing-surface of the pavement; but it isusually within a margin of from five to eight per cent. of asphalticcement to one hundred per cent. of the metal described. Thematerialsasphaltic cement and metalare placed in an amalgamator andthoroughly mixed, after which, and while still hot and plastic, they aretaken to the locality where the pavement is'to be laid and spread upon aprepared surface, raked to the proper degree of thickness and trampedand rolled into a solid homogeneous mass or coating. The surface is thencovered with hydraulic cement, or, preferably, a mixture of hydrauliccement and sulphate of calcium in about equal proportions, after whichit is rolled again until cold and fit for use.

For street-work I prepare the base or substratum by first leveling offthe surface to the proper grade and placing thereon a layer of brokenstone, the larger stone being placed at the bottom and the smaller ontop. This mass of stone is then covered and the interstices filled withcoal-tar distillate and rolled into a solid mass or layer of therequired thickness. Upon the base thus formed is spread thebinder-course, consisting of small stone previously heated to about 150Fahrenheit and mixed with the prepared asphaltic cement hereinbeforedescribed, in the proportion of about one gallon of asphaltic cement toone cubic foot of metal. This mixture is laid evenly upon the preparedsubstratum and rolled to the required thickness, after which thewearing-surface is applied in the manner previously explained.

By preparing the binder-con rse with the asphaltic cement andinterposing it between the coal-tar distillate of the substratum and theasphalt cement of the upper or wearing face a more perfect amalgamation.of the several courses is effected and the life and endurance of thewearing-surface-the part most subject to decay-is increased andprolonged.

I do not claim herein the method of laying the pavement, nor thepavement itself, as con: tradistinguished from the method of preparingthe ingredients as herein described and claimed, said subject-matterbeing reserved in a divisional application, No. 290,038, filed November5, 1888.

Having thus described my invention, what I claim as new is 1. Thehereinbefore-described improvement in the art of manufacturing asphalticcement for use in paving compounds, which consists in distillingcoal-tar and asphalt together at a temperature of 450 Fahrenheit and notexceeding 500 Fahrenheit, and subsequently adding thereto coal-tar whichhas been heated to 450 Fahrenheit, substantially as described.

2. The hereinbeforedescribed improve ment in the art of manufacturingasphaltic pavements, which consists in heating coal-tar and crudeasphalt, in about the proportions named, to a temperature of about 450Fahrenheit and not exceeding 500 Fahrenheit, until the vapors arising atsaid temperature are eliminated, adding to said mixture a furtherquantity of coal-tar which has been deprived of its lighter constituentsby being subjected to a temperature of between 450 and 500 Fahrenheit,and subsequently adding to the asphaltic cement thus formed mineralsubstances at a temperature not exceeding 250 Fahrenheit, substantiallyas described.

3. The hereinbefore described improved process of forming vulcanitepaving compounds, which consists in mixing comminuted mineralsubstances, of which sulphur forms one ingredient, heated to atemperature not exceeding 250 Fahrenheit, with an asphaltic cementcomposed of coal-tar distillate and native asphalt refined at atemperature not exceeding 500 Fahrenheit, substantially as described.

4. The hereinbefore described improvement in the art of manufacturingavulcanite paving composition, which consists, essentially, in refiningnative asphalt by heating it, together with distillate of coal-tar, at atemperature of about 450 Fahrenheit and not exceeding 500 Fahrenheit,adding, in about cium, stone dust, and mineral wool 01' asbestheproportions named, distillate 0f coal-tar tus, suljmtantially asdescribed.

which has been subjected to about the same 7 Y Y 7 temperature as theasphalt, and-subsequently ILLIAM RDOCIX' mixing with the asphalticcement thus formed \Vitnesses:

sand, hydraulic cement, calcareous gravel, THOMAS DURANT,

sulphur, carbonate of lime, sulphate of call MELVILLE CHURCH.

